Convergent Evolution of Morphogenetic Processes in Fungi
Eumycetes fungi are a diverse group of organisms whose evolution is characterized by frequent changes in nutritional strategy and the corresponding developmental programs. The reasons for this versatility are unknown. We previously discovered that the NAD
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Convergent Evolution of Morphogenetic Processes in Fungi Sylvain Brun and Philippe Silar
Abstract Eumycetes fungi are a diverse group of organisms whose evolution is characterized by frequent changes in nutritional strategy and the corresponding developmental programs. The reasons for this versatility are unknown. We previously discovered that the NADPH oxidase Nox2 and the tetraspanin Pls1 are used in two radically different cell types to achieve the same purpose: exiting from a reinforced cell, suggesting that convergent evolution of morphogenetic processes could account for the repetitive switches in trophic modes during fungal evolution. However, we recently observed that saprobic fungi are also able to differentiate appressorium-like structure closely resembling those of phytopathogenic species, arguing that the ability to differentiate such cells is an ancient property of filamentous fungi. Adaptation of parasitic and mutualistic fungi to plant may thus not solely reside in their ability to penetrate their host.
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Introduction
Fungi belonging to the Eumycetes (Opisthokonta) are a great success of evolution. Their ancestors switched from phagotrophy, the original eukaryotic trophic mode, to osmotrophy likely a billion years ago (McLaughlin et al. 2009). Since then they have diversified into hundreds of thousands species and possibly much more (Hawksworth 1991). They have invaded nearly all biotopes, from the deepest depths of the oceans to the top of the highest mountains all around the globe. They are even found in the arctic soils that remain frozen most of the years (Schadt et al. 2003). Their total biomass is huge and they greatly impact on their environment. They live either in parasitic or in mutualistic symbiosis with other organisms, S. Brun and P. Silar UFR des Sciences du Vivant, Universite´ de Paris 7 – Denis Diderot, 75205 Paris Cedex 13, France Institut de Ge´ne´tique et Microbiologie, UMR CNRS – Universite´ de Paris 11, UPS Baˆt. 400, 91405 Orsay cedex, France e-mail: [email protected]
P. Pontarotti (ed.), Evolutionary Biology – Concepts, Molecular and Morphological Evolution, DOI 10.1007/978-3-642-12340-5_19, # Springer-Verlag Berlin Heidelberg 2010
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or as free living saprobes. The saprobes participate in the global carbon cycle, especially they degrade highly recalcitrant materials that no other organism may and regulate soil health by producing humic acids. As mutualistic symbionts, the mycorhizal and endophytic fungi increase plant fitness and those present inside the digestive tract enable many insects and mammalian herbivores to use the hard-todigest plant materials as food. Similarly, the mutualistic lichens are an important component of many extreme biotopes. Parasitic fungi are known for nearly all organisms (even fungi!), but they are especially important for plants and insects. These have a tremendous impact on the dynamics of natural populations but also on domesticated plants and animals. The feeding, dispersal, and “behavioral”
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